How computer blunder hit the UK’s Test and Trace system

Current figures show that, for each person who tests positive, tracers find three others who have been in close contact and who might be infected, amounting, in this case, to 47,523.

Research by Imperial College London shows that 20 per cent of people who have been in close contact with an infected person are infected, which would suggest around 10,000 contacts of the original cases may now have contracted the virus.

Old format caused spreadsheet glitch

The problem arose with a centralised spreadsheet created to automatically collect data logged by private companies carrying out swab tests, so results could then be fed into the Test and Trace system as well as into Government dashboards showing infection rates.

However, PHE used an old format for the spreadsheet, which could only record 65,000 rows of data, when modern versions can record millions. 

Because each positive test created multiple rows of data, the spreadsheet could only record around 1,400 cases.

In previous weeks, the number of positive tests recorded remained below this cap. However, the surge in infections last week – which followed repeated warnings that a surge was expected – saw the data cap hit, so thousands of cases went unrecorded. 

Huge surge in cases

Updated data now shows huge rises in infections occurring in areas that looked as though they were coping. 

Nottingham, which was not on the Government’s Covid “watch list”, has seen weekly cases rise to 283.9 per 100,000, which last week would have made it as the worst area in the country when compared with the pre-adjusted figures.

Although the Department for Health has insisted the new figures do not impact the list or alter current restrictions, Nottingham residents have been warned to brace for lockdown (the graphic below shows rates of infection across the UK).

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